There are many mining and industrial sites in which soil is contaminated with one or more of Pb, Cu or Hg. The Pb, Cu, or Hg contaminants may be in the form of metals, or compounds of the metals, all of which are toxic to humans in some degree. The form that contaminants take depends on their origin, the environment in which they are found, and the length of time they have been exposed to this environment.
When such contaminants are in the soil in the form of relatively large particles, for example, greater than about 65 mesh, the soil may be treated by soil washing techniques. Typically, however, the contaminants are in the form of particles of smaller size.
When the contaminants are in the form of relatively small particles, soil washing techniques are not practical. In such cases soil treatments typically include solidification, vitrification and capping. Such techniques, however, do not remove the contaminants, but merely trap them in the soil in a way that they can not leach out into water sources and the like where they could pose a danger for humans. As such, these treatments may be considered less than ideal. These treatments also usually require a high temperature, and are thus generally energy intensive and expensive.